How to wean my 18mo off breast feeding?

Hi, any mommies with experience on this? My 18mo is very reliant on my boobs and refuse to take the pacifier / milk bottle from young. I’ve been direct latching her. It was a lot of convenience at the start but now I am finding it so hard to wean her. I am currently pregnant and I definitely don’t have much milk supply. She is obviously addicted to comfort latching and not really because she wants to drink milk. Any ways to this? I get cramps from her latching which is not good for the current pregnancy. And I latch her pretty often during the day / through the night..